The invention relates to apparatus for the radial shaping of objects such as shaped spindles for rotors and stators of single spindle pumps, and the like.
Arrangements are known for manufacture of rotors for single spindle pumps from an elongate seamless tube by cold shaping methods in which a forming tool having at least three forming jaws is controlled either by a press as it is the case disclosed in the Czechoslovak Certificate of Authorship of an Invention No. 135,995, corresponds to U.S. Pat. Nos. 3,606,789 and 3,740,811, or by a direct drive of individual sliding shoes provided with forming jaws by way of eccentrics. The first mentioned arrangement requires the application of a special press, which by means of a wedge situated on the press ram acts via rods and a pressure plate on faces of forming jaws which are thus inserted into a conical space of a casing.
A drawback of this arrangement is the high power requirements for the press in order to overcome resistances between the wedge, rod, pressure plate and jaws. Further disadvantages lie in the substantial wear of working parts of the arrangement, their frequent seizure and damage by cracks.
The second arrangement requires no special press as it has its own drive and transmission to the individual sliding shoes which are provided with the forming jaws. Its drawback is, however, that its working stroke is constant and cannot be changed in the course of operation. The drive of this latter arrangement requires, therefore, the construction of a transmission gear and of transmissions which increase the size and weight of the proper arrangement.
It is an object of the present invention is to provide an arrangement for radial shaping, particularly for shaping of objects having the form of a spindle, which would not require special transmissions for driving and which would enable the change of the working stroke in the course of operation corresponding to different requirements during shaping. These and other objects will be obvious from the following disclosure.